The continuous development of science and technology makes the electronic display technology is constantly upgrading. People are also seeking a larger screen, higher resolution and more exciting visual effects. An organic light-emitting diode (OLED) screen has advantages including a high contrast, a wide visual angle, a high saturation, a low power consumption etc. These advantages undoubtedly push the OLED screen to the forefront of display market development.
A basic structure of the OLED mainly includes: an electron transport layer, a light-emitting layer and a hole transport layer. When a power supplies an appropriate voltage, electrons and holes are respectively injected from a cathode and an anode to an organic functional film sandwiched in between the electrodes. The injected electrons and holes are respectively migrated from the electron transport layer and the hole transport layer to the light-emitting layer. The electrons and holes recombine to produce excitons. The excitons are migrated under an action of an electric field to transfer an energy to luminescent molecules and to excite the electrons to transit from a ground state to an excited state. An excited state energy produces photons through a radiation transition.
The liquid crystal display (LCD) is a voltage-driven element, The liquid crystal can normally operate if a required voltage is provided within a required time. The LCD is not sensitive to current changes. However, the OLED is a current-driven element, so different currents result in different brightness of the OLED. Therefore, a pixel driving circuit of the OLED is more complex.
The current display panels employs the same driving circuit, so it is difficult to proceed a PCB layout scheme under a condition that meet with design requirements including devising requirements of a high pixel per inch (PPI), a high screen ratio and a high resolution.
With the development requirements of the high PPI, narrow borders and a high resolution for the display screen, a driving circuit which adapts to the high PPI requirement and overcomes a layout space issue is required urgently.